@@ -4,5 +4,5 @@ Contributions Many people have contributed to Pysolar since its inception. Thanks to Holger Zebner, Pietro Zambelli, Sean Taylor, Simeon Obinna -Nwaogaidu, Timmie Chelsen, and Lahmeyer International for their +Nwaogaidu, Tim Michelsen, and Lahmeyer International for their contributions of code, bugfixes, documentation, and general encouragement. CONTRIBUTORS.markdown @@ -1,26 +1,39 @@ -Pysolar performs calculations useful for the development of photovoltaic -systems. Rough steps for use, until either forever or I have time to +Pysolar is a collection of Python libraries for simulating the irradiation of any point on earth by the sun. It includes code for extremely precise ephemeris calculations, and more. + +Rough steps for use, until either forever or I have time to write more documentation: 1. Install python. -2. Get to a prompt that looks like: >>> -3. >>> import solar -4. >>> import datetime -5. >>> d = datetime.datetime.utcnow() -6. >>> lat = 42.0 -7. >>> long = -71.0 -8. >>> solar.GetAltitude(lat, long, d) -9. >>> solar.GetAzimuth(lat, long, d) - -For better examples of usage, check http://pysolar.sourceforge.net/#examples - -At this point, Pysolar has basic functionality, but it is relatively untested. -I did validate it against the data in a paper by Reda and Andreas; it agrees -to 4 significant figures, but that's just one data point. - -If you use Pysolar, please let me know how accurate it is. It's difficult to -measure sun location with great precision, but I'd love to hear reports of -"Yeah, it worked to within a degree over the course of an afternoon in Spain." - -Brandon Stafford -first_name @ pingswept org \ No newline at end of file +2. Get to a Python prompt. +3. Execute code: +<pre> + import datetime, solar + d = datetime.datetime.utcnow() + lat = 42.0 + long = -71.0 + solar.GetAltitude(lat, long, d) + solar.GetAzimuth(lat, long, d) +</pre> + +For better examples of usage, see [the examples on Github](http://wiki.github.com/pingswept/pysolar/examples). + +## Difference from PyEphem ## + +Pysolar is similar to [PyEphem](http://rhodesmill.org/pyephem/), with a few key differences. Both libraries compute the location of the sun based on [Bretagnon's VSOP 87 theory](http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1988A%26A...202..309B). Pysolar is aimed at modeling photovoltaic systems, while PyEphem is targeted at astronomers. Pysolar is written in pure Python, while PyEphem is a Python wrapper for the libastro library, written in C, which is part of [XEphem](http://www.clearskyinstitute.com/xephem/). + +## Validation ## + +Pysolar has recently been validated against similar ephemeris code maintained by the US Naval Observatory. In a random sampling of 6000 locations distributed across the Northern Hemisphere at random times in 2008, Pysolar matched the observatory’s predictions very accurately. The azimuth estimations correlated much more closely than the altitude estimations, but both agreed with the naval observatory’s to within less than 0.1 degrees on average. + +More details on [the validation page on Github](http://wiki.github.com/pingswept/pysolar/validation). + +## A request ## + +If you use Pysolar, please let me know how accurate it is. It's difficult to measure sun location with great precision, but I'd love to hear reports like, "Yeah, it worked to within a degree over the course of an afternoon in Spain." + +## Developer contact info ## + +[Brandon Stafford](http://pingswept.org) + +brandon at pingswept org + README.markdown 9d0fdf77d356da2e10818d2f3f4ceba4d03b53f2 Brandon Stafford brandon@pingswept.org http://github.com/pingswept/pysolar/commit/6b8bc63da99523ae2dd892d98354e19d6f42a6cb 6b8bc63da99523ae2dd892d98354e19d6f42a6cb 2009-04-10T20:34:58-07:00 2009-04-10T20:34:58-07:00 Updated README and CONTRIBUTORS. 70e4797f50f5f77ce74a635f9be575bcb545530e Brandon Stafford brandon@pingswept.org